Motor fuel



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UNITED STATES. PATENTT orifice v Ren de M. Taveau, Newburgh, N; Y., or-to The Texas Company, New York, N. 1., a corporation of Delaware No Drawing. Application June 1, 1933, Serlal No. 673,853

10 Claims. (01. 44-9 g This invention relates to improvements in mcontemplated may be methyl, ethyl, propyl, butyl tor fuels for internal combustion engines of the and other radicals of the higher homologues 'of Diesel or compression ignition type, and is parthe paraffin series, or the corresponding unsatuticularly concerned with the provision of acomrated radicals of the homologues of the ethylene bustion primer or accelerator in the fuel for the series. The 'aryl substituents include phenyl, 5 purpose of inducing ignitiein .at lower comprestolyl, xylyl and other homologues of the benzene sion pressures or compression ratios than would series. It is to be understood that I mayuse be possible without such an accelerator. substituted alkyl or aryl groups, such as aralkyl Time lag is a phenomenon which is prevalent and alkyl or aryl radicals containing halogen,

in practically all-types of compression ignition amino, hydroxy or methoxy substituents. Comengines and is defined as the length of time 00- pounds which are useful include, for example, dicurring between the entrance of the first pofiion ethyl-, diphenyl-, dltolyl-, ethyltolyl, dinitrodiof the fuel charge into the engine cylinder and its ethyl-, and dianisol-tetrasulfldes. subsequent ignition. Ti'me lag is principally re- The tetrasulfldesmay be prepared according to sponsible for undesirable engine operation char methods described in the literature to which ref- 15 acteristics known as detonation, misfiring, and 'erence is made, particularly Annalen, 359, 81 rough running, and the longer the time lag the (1907) and J. F. prokt. Chem., (2) 3'1, 207-13,- worse these conditions become. 'However,. time (1888). v lag with its accompanying evilscan be reduced 1 The quantity of the accelerator required .for

so ordinarily by either increasing the compression the purpose of reducing the compressionratio for ratio of the engine, or by changing the characterautoignition of the fuel oil in compression ignition isticsof the fuel itself in such a way as to, reduce engines is usually small; for example, 0.5 to 5.0% the compression ratio necessary for ignition. and preferably in the region of 1% by weight of Obviously the first-remedy, that of increasing the the fuel oil.

35 compression ratio, is not mechanically possible in The compression ratio for autoignition varies 28 many engines and-is undesirable in all since the with the fuel and is a property inherent inthe structural strength and weight of the enginegnust nature of the ingredients of which the fuel is be considerably increased in order to safely withcomposed; for example, isooctane, although stand the resulting higher pressures. Such a lighter than oils ordinarily found in Diesel fuels,- 80 change also tends to reduce the overall b performs well in spark-fired engines, but it is a 30 thermal efliciency of the engine. The second poor fuel for compre on ignition engines. On remedy, that of reducing the minimum onipres-- the other hand, n-he time has good ignition sion ratio necessary for the autoignition of the properties for 9. Diesel} fuel but it is a poor :fuel fuel, is therefore the only remedy in many in=- for spark-fired engin In comparing Diesel 86 stances and the bestin all instances. 1 oils, blends of iso-octan and n-heptane are-often It is the chief object of the present invention made use of as referenceduels, whereby high octo produce a novel fuel which will meet the comtane numbers, which indicate useful high compression ignition requirements for various Diesel pression ratios and characterize the desirable engines and to provide a simple and eflicient qualities in fuels for spark-firedengines, are usu- 9 method of treating fuels to form products havally indicative of undesirablequalities in coming the desirable compression ignition properties pression ignition engines;- and conversely, high from any oil or from various oils requiring widely heptane numbers characterize good Diesel fuels different compression ratios for autoignition. 'or those ignitable at low compression ratios but In accordance with the present invention I add indicatethat the fuels are poor for'spark ignition to s-high boiling or relativelynon-volatile fuel, engines.- In the examples that are to follow,'hepm such ascommonly used for compression ignition ,taiie numbers. i.- e., the percentageofheptane in engines, an accelerator comprisinga volatile poly a blend of n-heptane and 'iso-octane-wh-ich will sulfide, such as an organic tetrasulflde. I may give the same minimum compression rate as that usesymmetrical tetrasulfldes of the general forrequired to 'e'flect fautoig n'ition of the unknown mula R-SSSS"R=where Rmsybe analkyl fuel, will be used as'a measure ofdes irable ignior aryi substituent, or 'an-unsymmein'ieal comtion qualities instead of actual-compressionr 10s.- pound of the general formulaRSS-S- -S'-R' 1 The following e s w illustrate the vin which R and R are unlike constituents, say, ra n of't i v im 4 R an alkyl'or substituted aim, and R anaryl To a gas 011 f o e b a ti base ude oil or substituted aryl group. The alkyl substituents and having a heptane value (if-"64 addedap proximately 1% by weight of diethyl-tetrasulflde. The heptane value of the resulting product was 85, or an increase of 21.

To another sample of the same oil was added about the same amount of di-p-tolyl-tetrasulflde and the-heptane value of the mixture was 76, or an increase inheptane value of 12.

The above heptane. values were determinedon a cooperative fuel research variable compression engine adapted7to use -a standard Bosch solid injection fuel system.

Obviously many modifications and variations of the inventio as hereinbefore set-forth, may be made without eparting from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim: Y

1. The method of accelerating ignition of liquid fuels for internal combustion engines of the Diesel type wherein ignition of the fuel is effected compression of air in the engine cylinder, which comprises incorporating into the fuel prior to ignition in the engine, in sufficient amount to substantially reduce the compression ratio for autoignition, a compound of the general formula R-S-S-S-S-R in which R is a, hydrocarbon radical.

2. The method of accelerating ignition of liquid fuels for internal combustion engines of the Diesel type wherein ignition of the fuel is effected by compression of air in the engine cylinder, which comprises incorporating into the fuel prior'to ignition a small amount of a diethyl-tetrasulfide compound. V

3. The method of accelerating ignition of liquid fuels forinternal combustion engines of the Dieselignition in the engine, in sumcient amount to substantially reduce the compression ratio for autoignition, a compound of e general formula RSS-S-S R' in which R is an alkyl radical and R an ar'yl radical.

4. The method of accelerating ignition of liquid fuels for internal combustion engines of the Diesel type wherein ignition of the fuel is eflected by compression of air in the engine cylinder, which comprises incorporating in the fuel prior to ignition a small amount 01' di-p-tolyl-tetrasulflde compound. a

5. The method of accelerating ignition of liquid fuels'for internal combustion engines of the Diesel type wherein the ignition of the fuel is effected by compression of air in the cylinder, which comprises providing in the fuel-air mixture prior to ignition in the engine ethyltolyl-tetrasulnde in sufficient amount to reduce the compression ratio for auto ignition.

6. A fuel oil of the class of Diesel oils, for use general formula R-S-S-S-S-R', in which R I is an allgvl radical and R an aryl radical;

10. A fuel according to claim 9 in which the accelerating compound is ethyltoyl-tetrasulflde. 

